What stops a miner from generating each block with a different key to increase their future odds of generating blocks?

How are the identities listed? Do they stake their public keys anywhere?

Will this use a proof of work mechanism? If yes, will the “identity winners” have higher chances (higher target) of finding the next block? If that's also a yes, how's that different from the current protocol where there's only difference between those who own more computational than the rest?